The city of Perry issued a drinking water warning Friday.Officials said water samples showed elevated levels of nitrite in the water.Nitrite in drinking water is a serious health concern for infants less than six months old, officials said.Children below six months should not have water, juice or formula prepared using tap water. Instead bottled water should be used, officials said.Adults and children older than six months can drink the tap water.City officials said they plan to adjust clorine levels and drain and clean an elevated water tower next Wednesday to help reduce nitrite levels.People with questions can contact the Perry Water Department at 515-465-2562.